The present invention relates to a method and apparatus for manipulating containers for pulverulent, granular or piece goods. More particularly, the invention relates to a method and apparatus for filling preferably flexible inner envelopes (hereinafter called bags) while the bags are confined in preferably stiff outer envelopes (hereinafter called boxes).
It is already known to introduce flowable materials into containers wherein a collapsible box confines a deformable bag. As a rule, the bags are introduced into successive boxes at a first or assembling station, the resulting empty containers are thereupon transported to a filling station where the bags receive requisite quantities of a flowable material, and the open upper ends of the bags are thereupon sealed prior to complete closing of the boxes. Such procedure is known as the "bag-in-box" technique and has been found to be highly satisfactory for storage of a wide variety of flowable and/or other materials (e.g., biscuits) in bags which are confined or about to be confined in boxes.
Since the bags are normally filled subsequent to insertion into the respective boxes, each bag must be open at its upper end when it arrives at the filling station. The filling station is followed by the sealing station for the open ends of the bags. Such sealing is possible if the open ends of filled bags are accessible to the sealing instrumentalities. In the case of bags which consist of thermoplastic material, the sealing action can be carried out by the application of pressure and/or heat. This means that, if the bottom of a filled bag rests on the bottom of the respective box, the height or length of the bag must appreciably exceed the length or height of the box in order to ensure that the open upper end of a bag at the sealing station can be subjected to the action of electrodes which apply requisite amounts of heat so as to effect a sealing action. Such design of bags is necessary irrespective of the exact nature of sealing instrumentalities, i.e., also if the sealing action is achieved by the simple expedient of rolling a splice or the like.
The situation is aggravated due to the fact that, as a rule, flexible bags which are inserted into cardboard boxes or like outer envelopes are not filled to capacity. In most instances, the bags are filled to approximately 75 percent of their capacity which means that, when the open end of a filled or nearly filled bag extends upwardly beyond the respective box, a substantial quantity of the material of the bag must be cut away in order to ensure that the sealed bag will fit into its box. Alternatively, the upper part of the sealed bag must be subjected to a pronounced deforming action so as to force it into the upper portion of the corresponding box. The additional cost due to waste in the material of the bags is not too serious when the quantities of containers are small. However, the cost of wasted material of which the bags are made is extremely high if the containers are to store certain types of commodities (such as flowable granular or pulverulent foodstuffs) which must be produced in huge quantities. Furthermore, storage of certain commodities necessitates the use of special types of foils or other materials of which the bags are made, and the cost of such materials is sufficiently high to warrant each and every attempt at a reduction of waste in the material of the bags.